A technique has been hitherto suggested, wherein a surface modification method for a polymer member, which is based on the use of pressurized carbon dioxide such as carbon dioxide in the supercritical state or the like, is applied to a pretreatment for the plating. In this method, a modifying material (functional material) is dissolved in pressurized carbon dioxide, and the pressurized carbon dioxide, in which the modifying material has been dissolved, is brought in contact with a polymer member. Accordingly, the modifying material is permeated into the surface internal portion or the inside of the surface of the polymer member to highly functionalize (modify) the surface of the polymer member. For example, the present inventors have proposed a production method for producing a polymer member (molded article), wherein a surface modification treatment, which is based on the use of pressurized carbon dioxide as described above, is performed simultaneously with the injection molding to produce the polymer member (molded article) in which the surface of the polymer molded article is highly functionalized (see, for example, Japanese Patent No. 3696878).
Japanese Patent No. 3696878 discloses the following production method. At first, a resin is plasticized and weighed in a heating (plasticizing) cylinder of an injection molding machine, and then a screw, which is included in the heating cylinder, is sucked back so that the screw is moved rearwardly. Subsequently, carbon dioxide in the supercritical state (hereinafter referred to as “supercritical carbon dioxide” as well) and a modifying material (functional organic material) such as a metal complex or the like dissolved therein are introduced into a screw front portion (flow front portion) of the molten resin (melted resin) having a negative pressure (subjected to the decrease in pressure) as a result of the suck-back of the screw. In accordance with this operation, the pressurized carbon dioxide and the modifying material are permeated into the molten resin disposed at the screw front portion. Subsequently, the molten resin is injected and charged into a mold. In this process, the molten resin disposed at the screw front portion, into which the modifying material has been permeated, is firstly injected into the mold, and then the molten resin, into which the modifying material is scarcely permeated, is injected and charged. When the molten resin disposed at the screw front portion, into which the modifying material has been permeated, is injected, the molten resin disposed at the screw front portion is brought in contact with the mold while being pulled by the mold surface to form a surface layer (skin layer) in accordance with the fountain flow phenomenon (fountain effect) of the flowing resin in the mold. Therefore, when the production method described in Japanese Patent No. 3696878 is adopted, a polymer molded article is manufactured, in which the surface internal portion (inside of the surface) of the polymer molded article is impregnated with the modifying material (the surface is modified with the modifying material). For example, when a metal complex, which comprises metallic fine particles to serves as the plating catalyst, is used as the modifying material, the polymer molded article, in which the surface is impregnated with the plating catalyst, is obtained. Therefore, it is possible to obtain the injection molded article to which the electroless plating can be applied while it is unnecessary to roughen the surface with an etching solution unlike the conventional plating pretreatment method.
A method has been hitherto suggested in relation to the electroless plating method, wherein the electroless plating is performed by using an electroless plating solution containing supercritical carbon dioxide (see, for example, Japanese Patent No. 3571627 and “Surface Technology” Vol. 56, No. 2, P 83 (2005)). In the reference documents described above, the following electroless plating method is disclosed. That is, the electroless plating solution and the supercritical carbon dioxide are compatibly dissolved by using a surfactant, and an emulsion (emulsified state) is formed by the stirring or agitation to cause the plating reaction in the emulsion. In ordinary cases, in the electroplating and the electroless plating, the hydrogen gas, which is produced during the plating reaction, stays on the surface of the plating objective to cause a factor of the formation of pinholes in the plating film. However, when the electroless plating solution, which contains the supercritical carbon dioxide, is used as in the electroless plating method as disclosed in the reference documents described above, the hydrogen, which is produced during the plating reaction, is removed, because the supercritical carbon dioxide dissolves the hydrogen. Accordingly, it is stated that an electroless plating film is obtained, in which the pinholes are scarcely formed and the hardness is high.    Patent Document 1: Japanese Patent No. 3696878;    Patent Document 2: Japanese Patent No. 3571627;    Non-Patent Document 1: “Surface Technology” Vol. 56, No. 2, P 83 (2005).